module top_module (
    input a,
    input b,
    input c,
    input d,
    output q );//

    assign q = (~a&~b&~c&~d) | (~a&~b&c&d) | (~a&b&~c&d) | (~a&b&c&~d) |
	(a&~b&~c&d) | (a&~b&c&~d) | (a&b&~c&~d) | (a&b&c&d);

endmodule